Tardive dyskinesia is common in geriatric patients prescribed antipsychotics.1 However, it is important to recognize that other conditions occasionally may be responsible for abnormal involuntary movements in older people with chronic mental illness. Late-onset conditions sometimes have a different pattern of symptoms, compared with the more common, earlier-onset forms of these disorders, therefore they can be more difficult to diagnose.

CASE REPORT: Ms. J is a 71-year-old woman who was diagnosed with schizoaffective disorder 20 years ago. She had been discharged from mental health services and was cared for by her general practitioner. Her discharge diagnoses were schizoaffective disorder and “early tardive dyskinesia.” Her general practitioner referred her for specialist psychiatric review, stating that Ms. J’s tardive dyskinesia is becoming worse. He requests advice about commencing treatment with anticholinergic drugs or tetrabenazine. Ms. J lives alone in a low-care accommodation facility. Her mental state had been stable for the previous 8 years. She is able to manage activities of daily living and undertake simple domestic tasks. She has regular assistance with cleaning. Her meals are provided by “Meals on Wheels” and a family member manages her finances. She maintains regular social contact with friends and family. She is aware of the movements, but is not especially concerned and reports that her daily functioning is unchanged in recent years.

Medication records are unclear, but when she first became psychotic in 1990, she was treated with haloperidol, 20 mg/d. The dose was eventually reduced to 6 mg/d, but increased if she developed psychotic or mood symptoms. She had 1 course of electroconvulsive therapy. She was switched to risperidone, 2 mg/d, in 2002.

She had a minor stroke 5 years ago, resulting in mild dysarthria. There is no other relevant medical history.

On assessment, her mood is bright and she reports no psychotic symptoms. She describes some forgetfulness and makes an occasional inappropriate comment, but her general knowledge and short-term memory are intact. Detailed family history reveals that her paternal grandfather had been diagnosed with Parkinson’s disease, and her father had “twitches” before his death in his 60s.

Neurologic examination reveals a generalized chorea affecting the trunk and limbs, with a broad-based, choreiform gait. Her speech is slurred. Although she has some involuntary movements of the face—predominantly grimacing—she does not show the oral-buccal movements characteristic of tardive dyskinesia. The provisional diagnosis of late-onset Huntington’s disease is confirmed by genetic testing. The Huntington allele is moderately expanded with 41 repeats.

This case highlights the importance of careful review, family history, and neurologic examination of geriatric patients taking antipsychotics who present with hyperkinetic movement disorders. Tardive dyskinesia is known to be more common in elderly female patients with brain damage, and Ms. J fits this profile. However, the lack of choreiform movements involving the tongue and mouth is atypical, and her speech impediment is because of a stroke rather than being due to buccolingual dyskinesia. Late-onset Huntington’s disease is characterized by a predominance of motor symptoms and the usual cognitive and behavioral disturbance is less prominent.2 Ms. J’s need for support with meals, cleaning, and managing her finances does suggest some cognitive impairment, and neuropsychological assessment would be helpful.

The correct diagnosis means that Ms. J will receive appropriate care, rather than being treated for a condition she does not have. It appears that Ms. J’s father and paternal grandfather had undiagnosed Huntington’s disease. The diagnosis has significant implications for family members. They can choose genetic testing, and older relatives who carry the mutation can be promptly diagnosed and receive appropriate care when they develop clinical manifestations.

DISCLOSURE: The author reports no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.